I bought a í92 400E back in January, with 60K miles, after spending about 2 months looking. My agenda was similar to Johnís (JCE), but primarily I wanted low miles, no ASR, and a goooooood warranty. Starmark was out because of the vintage.
The earlier models offer the lowest cost due to depreciation. Anyway, after searching every source I could find in the nation and making around 90 phone calls (and there were an awful lot of cool stories, good and bad), I found one in Rochester that fit the bill. I had a MB dealer check the car out in greater than average detail, contacted the place where the car was serviced, did a car fax review. The mb dealer gave it a thumbs up. They also said that the car was a Signature car after itís original warranty expired. Signature is the Canadian version of Starmark.
Long story short, the car was a good combination of value and warranty. Even so, since getting it, Iíve just done a 60K mile tune up, replaced the center and rear mufflers, replaced the sneakers and wheels, and some other minor stuff. Iím a happy camper, and still have 45 months/45,0000 miles of warranty coverage remaining. Take your time, and find a *good* car. There is no reason to rush into something that you probably hope to have for quite some time.
BTW, if you haven't already done so, start by reading everything here you can find on the 400E/E420. Also, enjoy the opportunities to look and talk with folks about the different 400s you encounter. This is part of the learning process, and is very entertaining as well!
Good luck and enjoy the hunt!
'00 ML320 "Casper"
'92 400E "Stella"